fix compiler warnings - STM32F7 HAL Drivers: 'packed' attribute ignored

[nerdCopter]

• reference Fixed warnings in STM libraries about ignored attributes. betaflight/betaflight#9228

fixes:

./lib/main/STM32F7/Drivers/STM32F7xx_HAL_Driver/Src/stm32f7xx_ll_usb.c: In function 'USB_WritePacket':
./lib/main/STM32F7/Drivers/STM32F7xx_HAL_Driver/Src/stm32f7xx_ll_usb.c:820:7: warning: 'packed' attribute ignored for type 'uint32_t *' {aka 'long unsigned int *'} [-Wattributes]
  820 |       USBx_DFIFO(ch_ep_num) = *((__packed uint32_t *)src);
      |       ^
./lib/main/STM32F7/Drivers/STM32F7xx_HAL_Driver/Src/stm32f7xx_ll_usb.c: In function 'USB_ReadPacket':
./lib/main/STM32F7/Drivers/STM32F7xx_HAL_Driver/Src/stm32f7xx_ll_usb.c:846:5: warning: 'packed' attribute ignored for type 'uint32_t *' {aka 'long unsigned int *'} [-Wattributes]
  846 |     *(__packed uint32_t *)dest = USBx_DFIFO(0);
      |     ^